Some definitions that are used in this document. They may be not mathematically correct and used only for simplicity.

1.      Polygon - several segments placed together. The segments are straight lines or curves. It cannot intersect itself.

2.      Closed polygon - the segments do connect at the beginning and end. That is, you start to draw the line at a point and finish at the same point.

3.      Closed polygon with holes – the polygon has both outer and inner closed bounds.

4.      Open polygon - the segments do not all connect at the beginning and end. That is, if we draw the polygon starting at one point, we finish drawing at a different point.

You must use FT in AutoCAD.